Markets this year have been stunned by “black swans,” a term for highly improbable (and market-shaking) events that was popularized in a theory put forward by author and investor Nassim Nicholas Taleb. The unrest in the Middle East and the Japanese earthquake have had dramatic consequences for markets globally, and it’s fair to say were almost entirely unexpected.

So how does Tuesday’s news that Australia is likely to reject the ASX-SGX merger stack up? At least one analyst is going out on a limb by attaching the black-swan label.

But that’s just the headline (“Black-Swan Event—ASX-SGX Deal Rejection Implications”). The text of Citigroup Inc. analyst Robert Kong’s research note is more measured. It calls the timing of Australian Treasurer Wayne Swan’s comments—three weeks after SGX submitted its merger proposal to Australia’s Foreign Investment Review Board—a “surprise event,” an assessment that matches that of SGX Chief Executive Magnus Bocker, who said he was “surprised” by the timing.

So, not quite an earthquake or revolution. Both ASX and SGX shares experienced large movements on Tuesday, in opposite directions—but a rejection by Australia’s notoriously difficult regulator, the FIRB, can’t really be considered startling. (Bearing that in mind, the approval of another pending foreign takeover would be more of a shocker.)

Mr. Kong was not available for comment, and a spokesman for Citigroup declined to comment.

But if the end of the deal isn’t quite a jolt to the system along the lines of a nuclear disaster, or, say, a thriller involving psychotic ballerinas, that’s all right. As any journalist knows, sometimes it’s OK to have a little fun with a headline.

About Exchange

Exchange is The Wall Street Journal’s place for inside news, insight and ideas on Hong Kong’s business and finance community. Write to us at hongkong@wsj.com or follow Exchange on Twitter and Facebook.